Remote servers provide service to remote users. In recent years, even after marketing a working machine, maintenance information and the like are provided to a user by remotely monitoring an operating status of a working machine with a remote server. For example, Patent Literature 1 discloses a configuration that manages a component life of a working machine with the remote server.
On the other hand, Patent Literature 2 discloses a configuration that detects slippage of a belt of a CVT speed changer. However, according to the configuration disclosed in Patent Literature 2, it is necessary to prepare in advance a threshold value for comparison with a difference or a ratio between a theoretical value and an actual measurement value of a speed change ratio. Further, the remote server disclosed in Patent Literature 1 does not disclose a configuration that detects an abnormal condition in a power transmission system.